![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWegFpfcZ6JwHAKik0XThJ5l8Q5Q6RZ5HRXCJQy8j1dmjBXRH5uViX5ptsbcaDDg2WeHVyimP1X2B12PFX9-EZazrIkNSeTYysJk8AxIWNk6uL7rLR6Wsh3f6AlLUPQDXp2ShRIEXLomSI/s200/Joule-Doh-01.jpg)
Recently I have re-engineered my homebuilt joule-thief after a too heavy shake that broke one wire. It was a good chance to let my older daughter choose for a new container, and a new color.
An empty play-doh can laying around was chosen as the new night light. The lid holds just right a 1xAA container and a small SPST slide-switch. Wires hold up the LED.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8FXps1PBVC7MM9e_IbkHJ9VHmNN3W1A3bFwu7QaDTFuPRrpEjQ7HmLDjn-eZUjvItd7LKyMokxIaxVMp6uq76xOoxcRn2XBU3WVePv18Gh49Ccq7ZEGbDB0-Q70JpY0ukd_cRKRjwGs0x/s200/Joule-Doh-02.jpg)
The 5mm while LED gives a quite directional light beam, but the transparentish can allows the light to be diffused around.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhf2QamuzcQ1ZkJO31kTtarUvtSkGxCaXlVAKGo6p1gN9B2oHAejIF4JNwJzt68RouaMvMmkyHlKPYnesX1BOqcOs9m7jQYBfpdTgokLIiPnU98bcF6JFu_b85m-CotR7mWJ0jkBvnqqO9S/s200/Joule-Doh-03.jpg)
For those not familiar with the "Joule thief", it is an oscillating circuit that allows to light a LED out of a 1.5V battery (be it AA, AAA or button). It usually works down to 0.8V, so it is a very good way to drain all the juice from those batteries that won't work anymore in normal toys. This one has been running already for 5 nights off the same "officially discharged" AA battery.